weekend you will need a parking spot tough to come by in the city. cornell bernart"px >> reporter: finding parking in san francisco can be a mission impossible. >> drive around for half an hour sometimes. >> reporter: san francisco is one city in the bay area using smart parking technology which adjust prices at meters and sensors determine if a space is vacant many parking apps use the information to help you. officials admit it is only 90% accurate. >> anything as far as using new technology can't be absolutely perfect. what we've done is look at this on an ongoing basis. >> reporter: we downloaded the free sf park app, blue line indicated lots of empty spaces on hayes street near franklin we only found a crowded street. this time it appears the app let us down unless i'm missing one there is not a single space here. we are going to move on to another neighborhood. unscientific test took us to laguna street where the app showed there was parking, none here either, minutes later, success the app decked us to grove street and lots of spaces. -- have